Underground wire line core barrel apparatus



Feb. 4, 1964 L. A. BRAUN UNDERGROUND WIRE LINE coRE BARREL APPARATUS Filed July 24, 1959 5 Sheets-Sheet 1 f//////////N//////////J4 R @@U WN Feb. 4, 1964 L. A. BRAUN UNDERGROUND WIRE LINE coRE BARREL APPARATUS Filed July 24, 1959 5 Sheets-Sheet 2 INVENTOR 5o/vara 4. BaMa/v fframvavs Feb. 4, 1964 L. A. BRAUN UNDERGROUND WIRE LINE coRE BARREL APPARATUS 5 Sheets-Sheet 3 Filed July 24, 1959 @uw /aman Feb. 4, 1964 L. A. BRAUN UNDERGROUND WIRE LINE coRE BARREL APPARATUS Filed July 24, 1959 5 Sheets-Sheet- 4 WMI.

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Feb. 4, 1964 L. A. BRAUN UNDERGROUND WIRE LINE CURE BARREL APPARATUS 5 Sheets-Sheet 5 Filed July 24, 1959 ums UQ @N HBH United States Patent O 3,120,283 UNDERGRUND WIRE HNE CGRE BARREL APPARATUS Leonard A. Braun, St. Paul, Minn., assigner to E. J. Longyear Company, a corporation 'of Minnesota Filed .luly 24, 1959, Ser. No. 829,429 14 Claims. (Cl. 1752-246) This invention relates to the art of deep core drilling in formations where the drilling direction is other than a downward direction and to new and novel improvements in apparatus for so doing. More particularly, this invention relates to new and novel improvements irl wire line core drilling apparatus of the nature that is iiuidly propeilable to the bit end of the drill stem irrespective of the drilling direction, said apparatus including a new and improved core barrel inner tube assembly for receiving and retaining a core, a new and improved wire line overshot assembly for retracting said core barrel assembly from the bit end of the drill stem, and new and improved cooperating structure forming part of the drill stem and the core barrel inner tube assembly for retaining the core barrel inner tube assembly in position for receiving a core.

This invention has been made in order to provide wire line core barrel equipment for overcoming problems of the nature set forth hereinafter which are encountered in using core barrel equipment of the prior art. One of the problems encountered in using the wire line core barrel equipment of the prior art is that if an outer diameter of the core barrel inner tube assembly is suiiciently large in order to form a fluid seal with the drill stem so that said assembly may be readily fluidly propelled to the .bit end of the drill stem and the drilh'ng direction is at an angle below the horizontal, the retraction of the core barrel by wire line equipment including an overshot assembly is a relatively slow process since the assembly in being retracted would force most of the uid intermediate said assembly and the outer end of the drill stem outwardly through the `outer end of said stem. Otherwise if the assembly were rapidly retracted, the wire line would break or else a very heavy wire line would have to be provided and a large amount of power would have to be expended in rapidly retracting the overshot assembly and the core barrel Ainner tube assembly. ln the event that the drilling direction were in a near horizontal or an upward direction, the aforementioned fluid would not have to be pulled out of the drill stem as the assemblies were retracted but rather there is present the problem of disposing of the duid that would drain from the drill stem as the aforementioned assemblies are retracted. lf the distance between the outer ends and the bit end is large, then likewise the quantity of lluid to be disposed of would be large.

Further, using the wire line core barrel equipment of the prior art necessitated that a smaller diameter of core be taken than that by using the `core barrel inner tube assembly of this invention even ythough a drill stem of the same internal diameter were used in both cases. That is in the prior art equipment, the outer diameter of the core receiving tube had to be of sutiiciently reduced diameter so that it would pass a hanger coupling that is provided to retain the core barrel inner tube assembly adjacent to but out of contact with the bit. Since the core barrel inner tube assembly of the prior art is held out of contact with the bit, a uid channel is provided between the outer peripheral surface of the inner tube assembly and the inner peripheral surface of the drill stem..

Using apparatus of this invention does away with the necessity of using a hanger coupling and still provides apparatus for centering the core barrel inner tube assembly in the drill stem and at the same time makes pro- "ice vision to allow fluid to pass from the annular space between the inner peripheral wall of the drill stem and the outer peripheral wall of the core barrel inner tube assembly and thence to pass radially inwardly through the aperture of the annular bit. |Ihat is, by using apparatus of this invention wire line core barrel equipment is readily useable for exploratory drilling from underground locations suoh as, for example, mines, for drilling in a direction that is horizontal, upwardly (including the interior of a drilling direction that is directly overhead), or downwardly, and still be able to provide core barrel inner tube assembly setting structure wherein there can be obtained a larger diameter core than with equipment of the prior -art that includes the same diameter drill stem having a core receiving tube of the same wall thickness and without having to retract the core barre-l apparatus from the bit end of the drill stem at a relatively low rate of speed and/or having to make provision for the disposal of a major portion of vthe drilling huid located in the drill stem between the outer edge of said drill stem `and the core barrel equipment in the bit end of the drill stern.

This invention relates to and forms improvements in the inventions covered by U.S. patent applications, Ser. No. 761,889, filed September 18, 1958 and Ser. No. 657,- O01, tiled May 13, 1957 and U.S. Patent, Ser. No. 2,829,- 868, issued April 8, 1958 which are incorporated herein by reference.

In order that the invention described herein may be more fully understood, the meaning of certain terminology as used in the specification will be set forth. The term inner refers to the portion of the drill stem or of an element of an assembly in its position for use in the drill stern which is located closer to the bit attached to the drill stem thany any other portions of the drill stem or elements being referred to, except where the term refers to transverse circumference or diameter of the drill stem. The term outer refers -to that portion of the drill stem or of an element of an assembly in its position for use in the drill stem which is located closer to the mouth of the drill hole than the other portion of the drill stem or element being referred to except where the term refers to a transverse circumference or diameter of an element or the drill stem. The terminology other than a downward direction refers to a drilling direction which is sufficiently inclined from a downward vertical direction so that apparatus positioned in the drill stem does not free fall toward the bit end of the drill stem. Even though the terminology other than a downward direction has been defined, it is to be understood that the apparatus of this invention may be utilized where the drilling direction is directly downward or a suiciently [downwardly inclined direction so that apparatus positioned in the drill stem would free fall toward the bit end of the drill stem.

The purpose of this invention is to provide new and improved wire line core barrel apparatus for core drilling in other than a downward `direction wherein said apparatus is fluidly propelled to the bit end of a drill stem and that permits flu-id to readily bypass said apparatus when the apparatus is being retracted in the drill stem. Another object of this invention is to provide new and improved wire line core barrel apparatus that is uidly propellable to the bit end of the drill stem, including structure for latohingly seating a core barrel inner tube assembly in the bit end of a drill stem which has a core receiving barrel of an outer diameter that is substantially equal to the inner diameter of the drill stem along the major portion of its longitudinal length.

A still further object of this invention is to provide a new and improved core barrel inner tube assembly constructed to be readily fluidly propelled to the bit end of the drill stem and automatically latched in place at the bit end of the drill stern irregardless of the drilling direction, permit the fluid to readily bypass the assembly when said assembly is latched in position at the bit end of the drill stem and permit the fluid in the drill stern to readily bypass the assembly when it is being retracted with wireline apparatus. A still additional object of this invention is to provide a new and improved wire line overshot assembly that may be readily fluidly propelled to the bit end of the drill stem regardless of the drilling direction and that readily permits fluid to bypass the assembly when said assembly is being retracted inthe drill stem. Another object is to provide a new and improved wire line core barrel apparatus that includes a centering ring and a spacer ring for centering and retaining the corerbarrel inner tube assembly in the bit end of the drill stem and still permit a larger diametric core to be taken than that previously possible with the wire line core barrel equipment ofthe prior art wherein the same size drill stem is used in each case and uid is passed by the respective assembly in the drill stem. A still additional object of this invention is to'provide new and improved wire line core barrel apparatus that includes a core barrel inner tube assembly having an inner edge that seats on an annular shoulder of a'drill bit and still permits fluid to readily pass between the inner end of the core barrel inner tube assembly and the drill stem to flow outwardly through the drill bit aperture and thence over the face of the bit.

Other and further objects are those inherent in the invention herein illustrated, described, and claimed and will be apparent as the description proceeds.

To the accomplishment of the foregoing and related ends, this invention then comprises the features hereinafter fully described and particularly pointed ont in the inner tube assembly of this invention and the drill stemk used for core drilling inother than a downward direction, said drill stem being broken away to illustrate the core barrel inner tube assembly in a latched position forY receiving core;

FIGURE 2 is an elevational view of thel hydraulic Vmechanism including fluid connections, the core barrel inner tube assembly and the drill stern used for core drilling in other than a downward direction, the drill stem beingk shown in section to illustrate the overshot assembly of, this invention being uidly propelled to the bit end of the drill stem for retracting a core barrel inner tube assembly;

FIGURES 3 and 4 when arranged one above the other, with the center lines aligned with FIGURE 3 at the top and FIGURE 4 at the bottom, form a composite longitudinal section through the core barrel inner tube assembly of this invention and the drill stem, said assembly being shown in a latched position. The meeting line between FIGURE 3 (at the top) and FIGURE 4 (below) is at the line A-A; Y FIGURE 5 is a longitudinal section of the outer end portion of a core barrel inner tube assembly in a drill stem for illustrating the fluid propel position of said assembly, saidV figure being similar to FIGURE 3 exceptV that it illustrates the relative positions of the members of said assembly as it is being uidly propelled towardV barrel overshot assembly of this invention, said overshot,-

assembly, said figure being similar to FIGURES 3 and Y 5, except that it illustrates the relative position of the members of said assembly as the assembly isV beingV retracted;

FIGURE 7 is an enlarged fragmentary sectional view of the inner end of the core barrel inner tube assembly and the drill stem illustrated in FIGURE 4, said view illustrating the new and improved spacer ring ofV this invention;

FIGURE 8 is a. transverse section of FIGURE 7 taken along the line and looking in the direction of the arrows 8 8 to illustrate the seating of the spacer ring in the annular bit, the core lifter case not being shown in said view;

FIGURE 9 is an enlarged fragmentary longitudinal sectional view of the lower end of a second embodiment of `a drill bit and a core lifter case positioned therein;

FIGURE l() is a longitudinal section rof the core assembly as illustrated being fluidly propelled towards the bit end of the drill stem;

FIGURE 11 is a longitudinal section of the overshot assembly shown in FIGURE 10, said view illustrating the retract'position of the overshot assembly as said assembly retracts a core barrel inner tub/e assemblyfrom the bit end of the drill stem. Y

Referring now to the drawings and in particular to FIGURES 1 and'V 2, there is illustrated a hollow drill stern 16 which is made up of sections of pipe coupled together and having an annular bit 15 mounted on the inner end thereof and being fluidly connected to a hydraulic pump 25 at the outer end, said drill stem being used to take a core from an earth formation 16. As may be notedin FIGURE 1, the longitudinal axis of the drill stem extends in a horizontal direction such that a core sample may be drilled from an earth formation in other than a downward direction. As Will subsequentially appear, the apparatus of this invention is particularly useful when the wire line core barrel equipment is to be used for recovering core samples where the direction of drilling is other than that wherein a core barrel inner tube assembly will fall to the bit end of the drill stem and Where said core barrel assembly is to be retracted at a relatively high rate from the bit end of the drill stem by use of a wire line overshot assembly Vthat is fluidly propelled to the bit end and still permit Vin a conventional manner by power means (not shown), Y

said means not forming a part of this invention and therefore will not be further described.

in order that the core barrel inner tube assembly may be lluidly propelled to the bit end of the drill stern, a water swivel, Vappropriate fluid lines, 4and valves are provided for -tluidly connecting the hydraulic pump .to the drill stem, said pump being mounted on a horizontal base 29. The water swivel enclosed by the bracket Z0 is threadedly connected to the outer end of the drill stem 10, the male threaded portion 21 of Ithe swivel being attached to lthe louter end olf the ldrill stem. The water swivel is of conventional construction and :therefore will not lbe further described. It is to be understood that even though the member 2'@ is reifer-red -to as a water swivel the iluid -used inthe system described may beY a liquid such as water or specially prepared aqueous or other `liquid suspensions containing clay or the like, or they may tbe gases such asco'rnpressed lair, nitrogen or other gaseous fluids. Y

The water swivel 20 is iluidly connected to the hydraulic pump 25 by pipe 22, T-joint 23, and pipe 24, the pipe 22 being connected to the louter end portion of the Water swivel from threaded pontionrl. The T-joint `23 is connected intermediate the pipes 22, 254 so that theY erdiaust line 23 may be fluidly connected to the fluid pressure system. The exhaust line 28 extends from the T- joint to a sump, there being an exhaust valve 26 located in said lme so that the drill stern may be selectively drained into the sump. A pressure control valve 27 is located in the pipe or pressure line 24 between the T- joint and the pump 25.

if desired a special valving such as a plug valve (not shown) may be provided in the drill stem a sucient distance inwardly yfrom the water swivel whereby the core barrel inner tube assembly 39 or 98 and the overshot assembly 125 may be retained in the drill stem intermediate said special valving and the water swivel so that the core barrel inner tube assembly and the overshot assembly may be inserted or taken out of the drill stem without the loss of a substantial quantity of duid from the interior of the drill stern even though the drilling direction is in an upward direction.

A core barrel outer tube assembly 12 -is attached to a pipe section of the drill stem lfor receiving and retaining a core barrel inner tube assembly generally designated 39. The structure of the core barrel outer tube assembly will be in part set forth hereinafter, a more complete description of the general type of an assembly which may be used is `found in the US. Patent 2,829,868, issued April S, 1915.

The core bmel outer tube assembly .12 is composed of a core barrel outer tube 36, a reaming shell 37 threadedly connected at the inner end of said sleeve, said shell having hard material such as diamonds on the outer reaming surface at 37B and an annular drill bit 15- for drilling into the earth formation i6 from which the core sample is taken, said bit being connected at the threaded male end 37A of the reaming shell.

The outer end of the core barrel outer tube assembly includes a coupling 3-1 which connects said assembly to the adjacent pipe section of the drill stem. At the opposide end of the coupling 3l Ifrom the aforementioned pipe section ka sleeve 32 is connected, said sleeve terminating at the opposite end with the threaded ymale end 32A. On the male end 32A there is threaded a wear coupling 33 having hardened lands 34 thereon.

The end 32B of the sleeve in conjunction with recess 33A in the wear coupling form a seat inside the surface of the wear coupling against which the latch dogs 49A, 4GB of the core barrel inner tube assembly are seated for electively retaining said assembly adjacent the drill bit. Also the end 32 has a projection iiange 32D which' extends as a partial cylindrical surface around and from the surface 32B. The side faces of this flange bear against the faces of the latch dogs and cause them and everything propelled thereby to rotate with the drill stern when said latch dogs are in the latched position as illustrated in FIGURE 3.

A recess is formed in the wear coupling adjacent the outer end of the sleeve 36 for seating the centralizing ring 35 which is of the same internal diameter as the coupling 31 and the portion of the drill stem located outwardly therefrom. The ring has beveled edge portions to more readily permit a core barrel inner tube assembly to pass therethrough. The internal diameter of the wear coupling 33 and the portion o-f the sleeve intermediate the centralizing ring and said coupling are of a larger diameter than the internal diameter of the remaining portion of the drill stem and the centralizing ring but are of a smaller diameter than the portion of the drill stem seating centralizing ring and the portion of the wear coupling forming the latch seat, said internal diametric portion of the wear coupling and the sleeve forming the enlarged diametric portion '38. The purpose of providing the aforementioned enlarged diametric portion is to permit fluid to bypass the outer end of the core barrel inner tube assembly and thereby decrease the rate of movement of the assembly as it approaches the bit end of the drill stem.

A spacer ring 39 having `an internal diameter of the same dimension as the intern-al diameter of the reaming shell 37 is press fitted into the bit Il5 to be located intermediate the male threaded end r37C of the rearning shell and the inwardly extending serrated annular flange portions 15A of the bit as shown in FIGURE 7. The spacer 'ring has the inwardly extend-ing ange portions 39A that seat on the l'bit flange 15A, said flange port-ions 39A. being of `smaller inner radii than the outer radius of the core lifter case 83 and a large inner radii than the radius of the opening ESB formed in the bit. A plurality of grooves 39B vare formed in the inner peripheral wall of the spacer ring (including between the atnged portions 39A) to extend the longitudinal length `of said ring for providing fluid channels through which' the fluid may pass from the annular space 52 between the core barrel inner tube `assembly and core barrel outer tube assembly to the bit opening 15B. The outer edge of the grooved portion of the ring is beveled at 39C to aid in seating the inner end of the core barrel inner tube assembly. The harige portions @A of the spacer ring hold the bit end of the core barrel inner tube assembly in a position spaced from the bit and absorbs the shock of the core barrel inner tube assembly as said assembly is seated in the bit end of the drill stem.

Referring to PGURES 3-6 inclusive, the structure of the core barrel inner tube assembly 39 will now be set forth. A more detailed description than given herein of some of the members of lthe core barrel inner tube assembly and of the drill stem may be found in U.S. patent applications Ser. No. 657,001 and 761,889.

The core barrel inner tube assembly 3l) includes a latch body 45 having latches 40A, 49B mounted thereon, a latch release tube 69 for retracting said latches, a core receiving tube Sil, a cap 65 threaded into the outer end of the core receiving tube, and a spindle 72 for connecting the cap to the latch body for limited movement relative to said cap. rl`he core receiving tube has the same type of threads at either end so that in the event the interior wall of the outer end thereof is damaged, the core receiving tube may be reversed end for end so that said tube does not have to be replaced. The core receiving tube has a replaceable core lifter case S3 threaded on the inner end thereof and a core lifter S2 mounted in the core lifter case. The core lifter case is of an external diameter to form a close lit with the grooved inner peripheral portions of the spacer ring. The general structure of the core lifter case, the core lifter and the functions of said structure are more fully set forth in US. Patent 2,829,868 and therefore will not be further described.

Formed in the outer end of the core receiving tube adjacent the cap 65 are a plurality of ports 65 for permitting the drilling fluid to escape from the core receiving tube as the core fills up said tube. The elongated spindle 72 which is threaded at the inner end 76 extends inwardly through the central aperture 63 of the aforementioned cap. Mounted on the threaded end of the spindle to abut against the cap is a resilient collar 73, which for example, may be made of rubber or Teilen, and abutting the collar is a washer 74. Nuts are threaded on the spindle to retain the aforementioned members thereon. A dowel in 69 secures the outer end of the spindle in an aperture formed in the inner end of the latch body, however, it is to be understood that said spindle may be threadedly secured to the latch body.

Mounted on the spindle adjacent the latch body are a pair of spaced squeeze washers 76, 77 and intermediate the squeeze washers is a resilient collar 78 which is axially compressable and radially expandable until it reaches the inner wall of the core barrel outer tube assembly 37 for pinching off or valving the annular space 52. The washers 76, 77 are of a diameter slightly smaller than the inner diameter of the drill stem in order to provide an annular uid channel around said washers but at the same time are suliiciently large to prevent shearing of the collar '78 when said collar is axially compressed. The resilient collar 7S, which may be, for example, made of Teflon or rubber, acts as a valve when an outward push of the core barrel inner tube occurs from the tube being filled with core or when the core jams in the tube. he collar 73 acts to absorb shock when the core barrel inner tube is being pulled in an outwardly direction while thecollar 78 provides a signal as set forth in US. Patent 2,857,138 and also absorbs shock when the core barrel inner tube is being seated.

Also mounted on the spindle 72 and located intermediate the squeeze washers and the cap are spacer washers 63, 64 and an anti-friction bearing assembly 79 that permits free rotation ofthe core barrel assembly with respect to the latch body. Thus when the latch body is rotated with the drill stem, the core receiving tube and associated parts may 'remain stationary with respect to the latch and thus protect the core sample which is in the core receiving tube from being damaged due to the rotation of the tube.

The generally cylindrical latch body 45 includes a main body 46 of a size to have the latch release tube dilslidably mounted thereon, an intermediate portion 47 or reduced diameter and an inner end portion 48 of an enlarged diameter but of a smailer diameter than the core receiving tube, said inner end portion having the spindle attached thereto by the aforementioned dowel pin. An elongated rectangular slot. l is provided in the central part of the main body, said slot extending from the apertured outer end 49 of the main body to plug 5t) which is the inner end portion of said main body.

' A through pin 55 is mounted in the main body 46 to extend through slots 5i, 59, there being on each end of the pin a retainer ring 55A of a diameter nearly the same size as the transverse Width of the slot 59. The pin extends radially outwardly through the slots 59 to approximately the outer diameter of the tube 60, said slots 59 being formed in opposite sides of the inner end of the latch release tube to extend transversely to openings 67 and being elongated in an axial direction. Pin 55 serves as pin locator for the two latch dogs 40A, 49B that are pivotally mounted on said pin in side by side relation in the slot 51. The hole S4 in the latch dogs through which the pin is inserted is slightly larger than the pin.

Each of the latch dogs are of long, at generally elon- Y gated construction and are spring biased transversely outwardly by springs 56 which are attached at one end (one spring to each dog) by rivets 61 to the side of the dogs opposite the cut-outs 49D formed in the latch dogs. The opposite ends of the springs bear against the peripheral wall of the latch release tube. Additionally each of the latch dogs is machined oft with smooth bottom radii at 48C and under both dogs is the support block 57 which has a matched rad-ii 57A. W`hen the bottom radii 46C of the dogs bear against block 57, the pin 55 has a slight clearance all around the hole 54. Block 57 is solidly held in place in the inner portion of the slot 51 by a pair of rivets 53 that do not extend radially outwardly beyond the latch body.

The axially extending openings 67 are formed in opposite sides of the tube so that the portions of the latch dogs 40A and 40B having the cut outs 46D may be extended therethrough to a latched position. Each of the openings 67 contain an enlarged portion 67A to facilitate machining said openings.

Y The plug is of a diameter to form a close tit with the inner peripheral wall of the latch release tube. The latch release tube includes an enlarged diametric or cylindrical portion 84 formed at the inner end thereof which forms a close iit with the inner peripheral wall of the centralizer ring when the core barrel inner tube assembly is in a latch position and forms a close fit with the Vdrill stem and the plug when the latch release tube is Iin a fluid propel position. The slots 5% are of a length to permit the enlarged diametric portion to be positioned axially on either side of the plug, the retainer rings bearing against the inner axial edge of slots 5@ when the core barrel assembly is in a latched position and against the outer axial edge when the latch release tube is fully retracted relative to the latch body.

Formed in the latch release tube outwardly from the enlarged diametric portion and closely adjacent thereto are a plurality of ports 85, said ports being located inwardly from the openings 67. When the core barrel inner tube assembly is in a latched position for receiving the core as drilled, the ports open inwardly into the annular space S7 between the centralizer ring and the intermediate portion 47. Thus the fluid channel 176 is formed whereby the iiuid may pass through the annular space 88 between the outer end of latch release tube and the adjacent portion of the drill stem, then radially inwardly through the ports 85, next through the annular space 87, thence outwardly between the inner edge of the latch release tube and the inner end portion of the latch body, the intermediate por'tion being of a longer axial length than the enlarged diarnetric portion 84. At the time the aforementioned fluid channel is formed, and the dogs are in a latched position, the spacer ring permits the iiuid to bypass the core lifter case and now through the bit opening and also centers saidV case.

. A plug 4l is fixedly mounted in the outer end or' the latch release tube by a pin 86 which is secured in appropriate apertures formed in the main body portion 42 of the plug and the tube. The main body portion of the plug has an outer diameter that forms a close t with the inner wall of the latch release tube.

The plug 41 includes a spear point 43 extending axially outwardly from the outer end of the latch release tube and extension 44 on the opposite side of the plug 41 that extends through the outer end aperture 89 when the inner tube assembly is in a fluid propel or latched position.V In a latched position the main body abuts against the outer end of the latch release tube and the extension aids in maintaining the latches in a latched position.

The structure of the rst embodiment of the core barrel inner tube assembly having been set forth, the second embodiment will now be described. The structure of the second embodiment of the core barrel inner tube assembly, generally designated 98 (see FIGURE 9), outwardly from the line B--B is the same as the iirst embodiment which has been described and illustrated in FIGURES 18 and therefore will not be further described.

The second embodiment of this invention 90 includes a core barrel outer tube (not shown) having an annular drill bit 91 threaded onto the roaming shell 37 The drill bit has an inwardly extending annular :Gange portion 92 that forms a shoulder 95 against which the inner end of the core barrel inner tube assembly 98 abuts.

The core barrel inner tube assembly 9S includes a core receiving tube (not shown) having a core lifter case 94 threaded on the inner end thereof,said case being of a diameter to rest on the shoulder but still not overlie the bit opening and having an outer diameter to Vleave an annular space Edil intermediate the core barrel inner tube assembly and the outer tube assembly. A core lifter 101 is mounted in the core lifter case similarly as that previously described for the rst embodiment of the core barrel inner tube assembly. The inner end of the core lifter case has formed therein serrations 96 in order to permit uid to flow radially inwardly from the annular space l0@ through the bit opening and then outwardly over the face of the drill bit. Except for the aforementioned serrations the second embodiment of the core barrel inner tube assembly may be of the same construction as the lirst embodiment described heretofore. An advantageV in utilizing the second embodiment of the core barrel inner tube assembiy over the iirst embodiment is that the core barrel inner tube assembly of the second embodiment encloses the drilled core right up to the annular ange of .the bit.

The apparatus of my invention for receiving the core having been described, I will now set forth my new and improved overshot assembly 125 and the apparatus used therewith for retracting the core barrel inner tube assembly from the bit end of the drill stem. The aforementioned apparatus includes a drill stem casing head, generally designated 11G, which is attached to the head end 1S of said drill stem after an overshot assembly has been inserted in the head end of the drill stem. The aforementioned drill stem casing head is used to form a Huid connection between the pipe 22 and the head end of the drill stem and also to permit a wire line to be drawn therethrough.

The drill stem casing head 11@ includes a head coupling 111 having male threads at one end thereof which are threaded into the head end of the drill stem and having a transverse aperture 111A formed in the intermediate circumferential portion into which one end of the iluid swivel 112 is threaded. The opposite end of the uid swivel is iluidly connected to the pipe 22.

On the outer circumferential surface of the head coupling 111 adjacent the outer end thereof, two pairs of spaced plates 113 are located diametrically across from one another. A latch 114 having a hooked end 114A is pivotally mounted between each pair of plates by the pivot pin 114B. The latched position of the latches 114 are shown in solid line in FIGURE 2 while the unlatched position is shown in dotted lines.

A stufling box 115, which has a cylindrical recessed portion 115A for mounting the gland 121 is inserted in the open end of the head coupling and is secured thereon by rotating the hook end or the latches over the outer peripheral flange 115B of the stuing box. A pair of spaced O- rings 116, 117 are positioned in grooves formed in the outer peripheral portion ot the stuing box that is inserted into the drill stem.

The gland 121 is secured to the stuliing box by four spaced stud bolts 119 (only two shown) which are inserted in appropriate apertures formed in the flange portion 121A of said gland, and screwed into threaded apertures located in the studing box 115. Nuts 120 are threaded on lthe opposite end of the stud bolts to secure the gland in position. A central opening 121C, 115C extends through the gland and stuffing box respectively so that the wire line 122 may be inserted therethrough. If desired, the gland and stuft-ing box may be formed from split sections to facilitate the insertion of the wire line into the central openings.

Although a specic drill stem casing head structure has been set forth, it is to be understood that this is not to constitute a limitation on the invention since other structural members may be used to perform the same functions as the drill stem casing herein described.

To retract the core barrel inner tube assembly 3i) or 98 from the bit end of the drill stern without having to withdraw the uid in the drill stem out of the head end thereof, my new and improved overshot assembly, generally designated 125 has been invented. The overshot assembly may be simply dropped down on the end of the wire line if the drilling direction is in a vertical direction or may be iluidly propelled to the bit end of the drill stem irrespective of whether the drilling direction is other than a downward direction or a near vertical direction.

The overshot assembly 125 is generally cylindrical in shape and is made up of a main body 123 and valving portion 124. The main body 123 includes a generally cylindrical overshot body 129 that has an elongated rectangular slot 12S milled in the inner central portion theref to form two spaced overshot body segments 129A. The transverse cross section of each of the segments is of a similar shape but the segments are positioned 180 relative to each other segment. The longitudinal length of the lot 128 extends outwardly to the line 129B. A pair of pulling dogs 126 having jaws 127 which are shaped to grasp a spear head 43 therebetween are prol@ vided (see FIGURE 6). The pulling dogs 126 are disposed in face-to-face relationship in the elongated slot 12g and are pivotally mounted on the pin 130 which extends through the overshot body segments to be secured therein and through the overlapping hub portions 131 of the pulley dogs. A coil compression spring 132, which is seated upon pins 133 (there being one pin welded in the outer end of each of the pulley dogs), normally urges the outer ends of the pulley dogs apart, and thus urges the jaws together in a grasping position while permitting expansion of the dogs to slide over the top or" the spear point when the overshot body has been lluidly propelled to the bit end of the drill stem.

The frusto-conical shoulder 135 formed on the lower end of the overshot body aids in centering the overshot assembly over the spear point, the inner surface of said shoulder being similarly shaped and slightly larger than the truste-conical portion of the plug 42. When the spear point is retained between the jaws 127 the shoulder 135 is within close proximity of the outer end of the latch release tube and thus imparts stability to the entire assembly 36 in respect to assembly 125 as said assemblies Sti, are retracted through the drill stem.

The overshot body has an end 129C of reduced diameter that is secured in the inner end of the generally tubular shaped jaw element 137 by a pin 149. The jaw element has an outer end of a reduced internal diameter to form an annular shoulder 137A for slidably retaining the enlmged cylindrical end 141A of the spindle 141 in the opening 133 that is enclosed by the jaw element. The port 139 is formed in the jaw element to open into the opening 138 adjacent the outer end of the latch body While a second port is formed in the jaw element to open into the opening 138 adjacent the shoulder 137A.

The valving portion includes a coupling element 143 and a spindle 141 having the aforementioned enlarged diametric portion 141A that forms a close tit with the opening 133, an intermediate portion 141B of a diameter that forms a close tit with the inner peripheral wall of the annular shoulder 137A and a threaded end 141C that is threaded in coupling element 143. The coupling element 143 is generally tubular shaped and is closed at its outer end by the cap portion 143A that has an aperture 14d formed therein that serves as an attachment for wire line or cable 122 which may be passed through the cap portion and knotted or otherwise fastened.

Mounted on the threaded end 141C of the spindle are an adjustment nut 151, a thrust Washer 152, an axially compressible and radially expansible resilient collar 153, and a second thrust washer 154. The second thrust washer is mounted on the threaded end to abut against the shoulder 141D formed at the juncture of the intermediate portion 141B with the threaded end portion 141C while the resilient collar is positioned in abutting engagement with the iirst thrust washer 152 on one side and the second thrust washer on the opposite side. The adjustment nut 151 is then threaded onto the threaded end portion to adjustably compress the resilient collar so that it forms a close lit with the inner peripheral wall of the drill stem, said adjustment nut being in abutting engagement with the coupling element on one side and the thrust washer on the opposite side.

Formed in the intermediate portion of the jaw element is a cross bore uid port 148. An axially extending opening 147 drilled in the spindle extends from the outer end thereof to open into the port 148. A plurality of transverse ports 146 are formed in the coupling element outwardly from the spindle to open into the opening 149 which is enclosed by said coupling element and the spindle.

The outer diameters of the coupling element 143, the jaw element 137, and the overshot body 129 are sufciently smaller than the internal diameter of the drill stem to provide an annular iluid channel between the Vmay' be followed.

engagea aforementioned elements and the drill stem. By providing the aforementioned portsV 1li-6, 148 and opening 147, provision is made for selectively bypassing fluid from one side of the resilient collar 153 to the opposite side thereof. That is, the intermediate portion of the spindle is of suicient axial length and the cross bore 148 is located so that when the wire line is retracted as illustrated in FIGURE ll, the coupling element, the spindle, and the elements mounted on the spindleare moved a suflicient distance relative to the jaw element so that the cross bar 148 opens into the annular space enclosed by the adjacent portion of intermediate Vportion 141B and the drill stem; and that when the aforementioned members of the valving portion 124 are moved inwardly relative to the main body 123 to a fluid propel position so that the washer 154 abuts against the jaw element, the ports 143 are closed by the Yinner peripheral wall portion of the annular shoulder 137A. The ports 136, 139 are provided to permit uid to enter into and exhaust from the opening 13d respective sides of the enlarged portion 141A as the main body and the valving portion are moved between a iluid propel and a retracted position. Y They structure of the core barrel inner tube apparatus of my invention having been described, I will now set forth the operation thereof. In the operation of the core taking apparatus of this invention, the core bit 15 and the drill stem Ylil are normally initially pulled back a small distance from the inner end of the hole being drilled for purposes of breaking the core which it has drilled. The elongated tubular section which makes up the -drill stem extends through the surface at which the hole is being drilled, the aforementioned surface very frequently being located underground as for example in the interior of a mine. The outer end of the drill stem is suitably held at the aforementioned surface for rotation and advancement by conventional drilling equipment. Y

Assuming that there is no coupling such as water swivel 2! on the other head end of the drill stem and that it is now desired to propel a core barrel inner tube assembly Edito the bit end of the drill stern where the core sample is being taken, the steps set forth hereinafter The core barrel inner tube assembly 30 is inserted into the outer end or" die drill stern and then water swivel 2t? is secured on the outer end of the drill stem and appropriate iluid connections are made so that the pump 25 will force fluid through line 24 and water swivel 2t! into the outer end of the drill stem. The duid pressure against the plug 41, the Vouter end of the latch release tube, and the enlarged diametric portion 34 of said latch release tube will force said members in an inward direction relative to the latch body to a fluid propel position. In the iluid propel position, the extension 44 abuts against the outer edge of the latch dogs as illustrated in FIGURE to prevent further inwardly movement of said tube relative to the latch body until the latches are seated in recess 33A and the enlarged iametric portion S4 in coniunction with the plug 50 substantially form a lluid seal with the adjacent portion drill stem so that fluid may not bypass the core barrel and inner tube assembly. As a result, the core barrel inner tube assembly is propelled to the bit end of the drill stem by the flow of tluid as indicated by arrows 175 (FIGURE 5).

As the enlarged diametric portion S4 of the latch release tube passes the inner end of the coupling 31 the core barrel/inner tube assembly decelerates since the enlarged diametric portion 3S of the drill stem permits iluid to bypass the enlarged diametric portion o the assembly. Due to the axial length of the opening-S67 formed in the latch release tube, once the core barrel inner tube Vassembly has moved to a position whereby the latches are opposite the latch seat 33A, springs 56 force the outer ends of said l tches transversely outwardiaY ly to a latched position. At the same time'as the latches are moved into a latched position or with a little additional longitudinal movement of the inner end of the core barrel inner tube assembly, the core lifter casing engages the flange part of the spacer ring and the movement of the latch body and the members of the core barrel inner tube assembly located inwardly therefrom is stopped. At this time the resilient collar .13 absorbs at least part of the shock resulting from the inertia of the spindle '72 and the members fixedly secured thereto.

Also as the latches move to a latched position, the latch release tube and plug 41 are free to move relative to the latch body until the main body of the plug 42 abuts against the outer end of the latch release tube. The aperture S9 in the outer end of the latch release tube is of suliicient diameter so that the fluid trapped intermediate the plug 41 and said outer end may escape through said aperture. lf the aperture is made suiiiciently small, the trapped duid will act to check the deceleration of latch release tube.

Additionally at the time the latches move to a latched position, the enlarged diametric portion 34 has already entered into the area encompassed by the centralizer ring. However, until the latch release tube has moved inwardly relative to the latch body as above described, the fluid path 17d established by the ports 35 being located inwardly of the plugy Sll is not opened. Once the latch release tube has moved inwardly relative the latch body, the duid ow path 176 is opened so thatthe fluid may dow from the pump through the drill stern, thence through the annular space S8 then radially inwardly through ports into the annular space S7, next radially outwardly through the opening between the enlarged diametric portion 84 and the inner end of the latch body, thence axially to pass through the annular space between the drill stem and the core receiving Vtube and finally through the grooved portion of the spacer ring toV ow axially outwardly through the bit opening. Y

The core barrel inner tube assembly fill is now ready to receive a core sample. Rotation of the drill stem may now be started and the cutting of the core begins. Because of the annular shape oi the cutting surfaces of the drill bit 15, the drilling action forms an annular shaped hole with a core being forced upwardly through the central aperture of the drill bit, through the core lifter case and the core lifter ring and upwardly into the core receiving tube.

After the core of a desired length has been cut, the drilling is stopped and the water swivel is removed from the outer end of the drill stem. Then the drillV stem is pulled outwardly a short distance, if it is necessary, to break the core. lf appropriate valves have been provided in the drill stem inwardly from the water swivel said valves may be closed to prevent fluid from draining from the drill stem where the drilling direction is upwardly and then the water coupling removed. Now the overshot assembly 125 with a wire line attached thereto is inserted into the drill stem, next the casing head is threaded on the outer end of the drill stem and then appropriate duid connection are made between the drill stern and the pump 25, and valves are sertV so that fluid may be forced through the line 24 into the casing head and then into the drill stem. The fluid pressure in the outer end of the drill stem forces the valving portion 12d inwardly relative to the main body 123 until the thrust washer 154 abuts against the jaw element so that the port 143, opens into the annular space between the Y spindle and the drill stemand thereby prevents fluid to bypass thel resilient collar 153. ln the event that a duid seal is not formed between the elements of the overshot assembly and the drill stern, the adjustment nut 151 may be turned in the appropriate direction toV expand the resilient collar to form a seal to prevent iiuid bypassing the overshot assembly. Now as additional tiuid is pumped into the drill stem, the entire overshot assembly LH i , 13 with the wire line attached thereto is fluid propelled toward the bit end of the drill stem.

When the overshot assembly has been propelled to contact the core barrel inner tube, the spear point 43 will force the jaws 127 apart so that said jaws will clamp onto the spear point. In the event that the jaws do not clamp onto the spear point, the wire line may be retracted to pull the overshot assembly a short distance away from the spear in order to utilize a hammering effect of the nature described in U.S. patent application, Ser. No. 761,889.

After the jaws have been clamped over the spear point, the wire line is retracted. The initial retraction of the wire line pulls the valving portion outwardly relative to the main body 123 (from the position illustrated in FIGURE 1G to the position illustrated in FIGURE ll) and thus opens the tluid channel or uid flow path designated by arrows 177 to permit fluid to pass through the annular space between the coupling element and the rill stem, next radially inwardly through the ports 14d into the opening 145, then through opening 147 and thence radially outwardly through the cross bore 143 to pass axially through the annular space intermediate the remaining portion of the overshot assembly and the drill stem.

Upon further retraction of the wire line, the entire overshot assembly is moved outwardly to pull the plug 41 and the latch release tube outwardly relative to the latch body and the latched dogs to retract said latch dogs. The elongated slots 59 are of an axial length so that the latch release tube may be moved relative to the latch body a suicient distance to move the large diametric portion 84 outwardly to space the inner end thereof axially outwardly from the plug 50 and thus provide the fluid channel or tluid ow path designated by arrows 173. The fluid ilow path 178 that is established by the plug 41 and latch release tube being moved to a retracted position extends from the annular channel between the drill stem and the outer end of the latch release tube, next radially inwardly through ports 85 into the slot 51, then axially through the slot to bypass the enlarged diametric portion 84, and thence radially outwardly through the space between the plug 50 and enlarged diametric portion 84 to pass axially through the annular channel between the remaining portion of the core barrel inner tube assembly and the drill stem. Once the latch release tube has been moved so that the retaining rings on pin 5S abut against the inner axial edges of the slot 59 further retraction of the latch release tube will cause the latch body and the other associated elements to be moved in an outward direction. In the event that the latch dogs are not unlatched by the aforementioned procedure, fluid pressure may be again applied to force the overshot assembly towards the bit end to provide a hammering etect of the nature described in U.S. patent application 761,887.

As may be apparent from the foregoing description, duid channels are provided to permit the lluid in the drill stem to bypass the overshot assembly and the core barrel inner tube assembly as said assemblies are retracted. Thus the aforementioned assembles may be retracted at a relatively rapid rate and the fluid is not forced out of the head end ofthe drill stem. Once the aforementioned assemblies have been retracted to the drill stem casing head end of the drill stem, if a valve is provided inwardly from the inner end of said assemblies, the aforementioned valve may be closed and thus prevent lluid from owing out of the drill stem once the drill stem casing head is to be removed (provided the drilling direction is in an upwardly direction). After the casing head is removed, the overshot assembly and the core barrel inner tube assembly are removed from the drill stem and an empty core barrel inner tube assembly may be again uidly propelled to the bit end of the drill stem in the manner previously described.

By providing a core barrel inner tube assembly such as that utilizes a centralizer ring and a spacer ring for retaining said assembly in a desired position at the bit end of the drill stem, the inner diameter of the core receiving tube may be of a larger diameter without decreasing the wall thickness of said tube and still use the same inner diameter drill stem than that wherein wire line core barrel equipment having hanger couplings is utilized'. Further the aforementioned rings hold the core barrel inner tube assembly in a centered position in the inner end of the drill stem.

In the event that the wire line core barrel inner tube assembly 9S is utilized, the serrated lower end of the lifter case provides a duid channel to permit the fluid to flow from the annular space between the core barrel inner tube assembly and the adjacent portion of the drill stem. The aforementioned serrated portion or the core barrel inner tube assembly absorbs the shock and wear as the assembly falls into place. Since the core lifter case is provided as a separate unit, in the event the serrated portion is damaged, said core lifter case may be readily replaced without having to replace other elements of the assembly.

As many widely apparently different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments herein.

What I claim is:

l. A core barrel inner tube assembly lluidly propellable to the bit end of a drill stem having a centralizer portion adjacent the bit end and a latch seat formed adjacent the centralizer portion, and retractable by an overshot assembly, comprising means for receiving a core sample as drilled, a latch body extending axially relative to the core sample receiving means, a latch mounted on said latch body for movement between a retracted position and a transversely outward position to seat in said latch seat, and latch release means for alternately retracting said latch and permitting said latch to be extended to a latched position, said latch release means including a cylindrical portion of a diameter to substantially form a fluid seal within the drill stem, said cylindrical portion having a fluid channel axially extending therethrough and an opening on either axial side of the said cylindrical portion to open into the space between the assembly and the drill stem portion, said latch body having a plug portion of a transverse cross sectional area to substantially uidly block said channel, said latch release means slidably retained on the latch body for limited axial movement inwardly toward and away from the latch body to at least three predetermined positions, said latch release means having an extension portion that contacts the latch in a retracted position for limiting the inward movement of the latch release means to one of said preselected positions, said plug in said one position being positioned relative to the cylindrical portion to block said fluid channel, said latch in a latched position providing a space for said latch release portion to move to permit the latch release means moving further inwardly toward the latch body to a second position for moving said cylindrical portion relative to the plug to provide an unblocked fluid channel, said latch release means having means including the aforementioned extension portion for the overshot assembly attached to for retracting said latch release means to a third predetermined position outwardly from said first and second position to retract the latch from a latched position and moving said cylindrical portion relative to the plug to provide an open iluid channel.

2. For rotary core drilling apparatus including a drill stem extending into a hole drilled into the earth, a core barrel inner tube assembly comprising means for collecting a core sample, a latch body connected to said core sample collecting means to extend in an axial direction relative thereto, a latch mounted on said latch body for movement between a retracted position and a position extending transversely outward from said latch body, generally tubular means slidably mounted on the opposite end of said latch body from said core sample means for alternately substantially preventing huid from bypassing said assembly in said drill stern and forming an open iluid channel to permit fluid to bypass said assembly, said latch body extending into the tubular means and having a plug to form a close fluid iit with an interior section'of the tubular means, said tubular means having a port opening into the interior thereof, said tubular means being movablerelative to the plug a sufficient distance to position said port on either side of the plug whereby said port on one side of the plug permits duid to bypass the assembly.

3. The apparatus of claim 2 further characterized in that said tubular means includes a grapple attachment on the opposite end thereof from the core sample means, said latch body having an axially extending opening formed in the outer end thereof, said latch being mounted in said opening and said grapple attachment having an extension portion of a shape to move into said opening to bear against the latch. Y

4. Apparatus uidly propellable to the bit end of a drill stem that has a latch seat and that extends inwardly into an earth formation and that is retractable by overshot means comprising a core barrel inner tube assembly including latch release means having a general cylindrical portion of a diameter that substantially forms a iiuid seal with the adjacent part of a drill stem in which said assembly is used, said cylindrical portion having a fluid channel extending therethrough to open on either axial side of the cylinder portion and means for alternately blocking said channel, and unblocking said channel and latchingly holding said assembly within close proximity of the bit end Vof the drill stem when said assembly is positioned for receiving a core sample, said last mentioned means including latch means for retaining said assembly in a latched position, said latch means including a latch mounted for movement between a latched position in said latch seat and a retracted position, said latch release means mounted on said latch means for limited axial movement yto atleast three predetermined positions, said latch means including plug means for blocking said fluid channel when the latch release means is in one of said positions, said release means including an extension portion contacting said latch in said one position for preventing said latch release means moving inwardly relative to the plug means until said latch is moved to a latched position and a portion shaped for the overshot means to clamp onto for moving said latch release means to a third predetermined position outwardly relative to said plug means for moving the latch to a retracted position and unblocking said iiuid channel.

5. A core barrel inner tube assembly uidly propellable to the bit end of a drill stem that has a latch seatand that extends inwardly into a hole drilled into an earth formation comprising means for receivably retaining a core sample, a latch body connected to the said core retaining means to extend in an axial direction relative thereto, a latch mounted on said latch body for movement between a retracted unlatched position and an outwardly t extending position in latching engagement with the latch seat of the drill stem, latch release means mounted on the latchbody for limited slidable movement relative thereto for alternately retracting said latch to a retracted position and permitting said latch to be extended to a latched position, said latch release means including a cylindrical portion substantially forming a uid seal with an adjacent portion of the inner peripheral wall of the drill stem and having a fluid channel extending axially through said cylindrical portion to open on either side of said diametric portion, said latch body having means for blocking said iluid channel when said latch release means is moved to a latch retracted position.

6. The apparatus of claim 5 further characterized in ha the CGI@ retaining msns includes a core lifter case at the inner end thereof and that there isprovided means mounted in the bit end of the drill stein for spacing said core lifterv case from said bit end, said last mentioned means having a uid channel formed therein to permit lluid to pass between the core lifter case and the bit end of the drill stem.

7. A core barrel inner tube, assembly fluidly propellable to the bit end of a drill stem that has a latch seat and that extends inwardly into a hole drilled into an earth formation comprising means for receivably retaining a core sample, a latchbody connected to said core receiw'ng means to extend axially outwardly therefrom, a latch mounted on said latch body `for movement between an extended position to seat in said latch seat and a retracted position, and latch release means for selectively retracting said latch, said latch release means being mounted on said latch body for limited inward and outward movement relative to the latch body, said latch body and latch release means each having means cooperating with one another to in a latch release means inward position form a solid transverse cross section of a shape and size substantially ithe same shape and size of the interior of the drill stem'V i and in a latch release means4 outward position to form an axially extending fluid channel to permit fluid bypassing said latch body and latch release means.

8. A drilling apparatus for drilling and recovering core from a hole drilled in any direction comprising ya hollow drill stem extending into the hole,

ya core bit mounted on the inner end of said drill stem for drilling the hole and forming the core sample, fluid pressure means `at the outer end of the drill stem and connected thereto for forcing fluid through said stem Land out across the bit face for lubricating and cooling the bit,

a core barrel inner tube assembly of ya size to pass through the drill stem, said assembly having a core receiving tube thereon at its inner end for receiving and holding core produced by the bit and grappleY coupling means at its outer end, said assembly forming a piston at a piston location along its length so as thereby to be propellable by the uid through the drill stem towards the bit, said assembly having a uid channel therethrough for bypassing said piston location, and valve means on the assembly for closing said channel when the assembly is being propelled by iluid pressure and opening said channel'when the bit isV in core receiving position proximate thebit, and when said grapple coupling means is pulled and grapple means comprising an elongated frame shaped so as to pass through the drill stem, said frame being shaped to receive a wire line connected to its outer end with the Wire line extended through the drill stem for pulling the frame toward the outer end of the drill stem, and `a movable grapple element` mounted at the inner end of the grapple means for cooperatively coupling engagement with lthe coupling means of the core barrel inner tube assembly, said grapple frame forming a piston at a piston location 'along its length so as to be propellable under uid pressure for movement through the drill stem towards the bit, and including a lluid channel bypassing said piston location, and valve formation on the grapple means and operable when the wire line is pulled for opening said uid channel and operable when the grapple means is pushed by fluid for closing said fluid channel. 9. The apparatus of claim 8 further characterized in that said v-alve formation includes a portion connected 'to the grapple element `and operable upon movement of the movable grapple element.

l0. lhe apparatus of claim 8 further characterized in that said valve formation includes a portion connected 17 so as to be operable by the Wire line when a wire line is attached thereto and is pulled.

11. A wire line core drilling and core sample recovering device comprising in combination a hollow drill stem having a coring bit attached to its end for drilling the hole and producing a core which, as the drill penetrates, will occupy an increasing length of the hollow drill stern proximate the bit,

a core barrel assembly ol elongted shape and of a size to slip through the drill stem, having at its inner end towards the bit a core receiving and transpor tube, and at its outer end away from the bit having thereon a grapple element which is made to be pulled,

said core barrel including, at a piston location thereon, lan outer surface acting as a piston so that when fluid pressure is applied to the outer end oi the drill stem which is the end away from the b-it the entire core barrel will be propelled through the stern towards the bit,

said core barrel including a iiuid channel therethrough bypassing said piston location, and

valve means operable for closing the channel when the core barrel is moved by liuid pressure applied to the outer end of the drill stem and operable for openthe channel when the core barrel is moved by pulling on its grapple element, and a cooperating grapple comprising an elongated grapple frame shaped so as to pass through the drill stem, and

shaped to receive a wire line connected to its outer end with the wire line extended through the drill stern for pulling the trame towards the outer end of the drill stern,

and a movable grapple element mounted on the inner end of the grapple frarne for cooperative coupling engagement with the cooperating coupling element of the core barrel inner tube assembly,

said elongated grapple frame being shape so as, in eiect, to form a piston at a grapple piston location along its length so as to be propellable under fluid pressure for movement through the drill stem towards the bit,

said elongated grapple frame including a grapple Huid bypass channel around said piston location thereon,

and grapple frame valve means on the assembly for closing said grapple frame iluid bypass channel when the grapple is propelled by iiuid pressure and for opening said iiuid bypass channel when the grapple is cooperatively coupled to the core barrel inner tube assembly and the grapple with said assembly coupled thereto are pulled through the drill stem by said wire line.

12. The apparatus of claim 1l further characterized in that the core barrel inner tube assembly and drill stem have cooperative latch means thereon for holding the inner tube proximate the bit as the core is produced, the latch means of the core barrel being movable thereon and connected to said grapple element thereon for mov-ement to unlatched condition when the grapple element is coupled to the lgrapple and the latter is pulled by the wire line,

i3. ln rotary core drilling apparatus comprising a tu- 'ou-lar drill stem, an annular drill bit mounted on one end of said drill stem, said drill stem having a latch seat formed in the bit end of the drill stem, core barrel inner tube means positionable in the bit end oi the drill stem 'for alternately receiving and retaining core as said core is drilled and retracting said core yfrom the bit end, said assembly having a latch mounted to seat in said latch seat and be retracted therefrom and a cylindrical diametric portion, and a centralizer ring mounted in said drill stem to abut against said cylindrical diametric portion for centering said assembly when the assembly is in a latched position, said apparatus being lfurther characterized in that the ldrill bit has an inwardly extending annular flange and that the core barrel assembly has a serrated inner end that seats in said iiange.

14. ln rotary core drilling laroaratus comprising a tubular drill stem, an annular drill -bit mounted on one end of said drill stem, said drill stem having a latch seat formed in the bit end of the ldrill stem, core barrel inner tube positionable in the bit end o-r the drill stem for alternately receiving and retaining core as said core is drilled and retracting said core 'from the bit end, said assembly having a latch mounted to seat in said latch seat and be retracted therefrom and a cylindrical diametric portion, and a centralizer ring :mounted in said drill stem to abut against said cylindrical diametric portion for centering said assembly when the assembly is in a latched position, said apparatus being 1further characterized in that die drill bit has an inwardly extending annular flange, said assembly having tubular shaped inner end and annular means mounted in the drill bit to seat in said flange for centering the said inner end and spacing said inner end from the drill blt.

References Cited in the le of this patent UNITED STATES PATENTS V1,719,144 Stokes et al. July 2, 1929 2,145,170 Frenzel Jan. 24, 1939 2,251,679 Kinnear Aug. 5, i941 2,260,320 Hoiloss Get. 28, l1941 2,294,521 Steadman et al. Sept. 1, 1942 2,508,285 Otis et al. May 16, 1950 2,769,6l5 Burgess Nov. 6, 1956 2,829,868 Piclrard et al. Apr. 8, 1958 

13. IN ROTARY CORE DRILLING APPARATUS COMPRISING A TUBULAR DRILL STEM, AN ANNULAR DRILL BIT MOUNTED ON ONE END OF SAID DRILL STEM, SAID DRILL STEM HAVING A LATCH SEAT FORMED IN THE BIT END OF THE DRILL STEM, CORE BARREL INNER TUBE MEANS POSITIONABLE IN THE BIT END OF THE DRILL STEM FOR ALTERNATELY RECEIVING AND RETAINING CORE AS SAID CORE IS DRILLED AND RETRACTING SAID CORE FROM THE BIT END, SAID ASSEMBLY HAVING A LATCH MOUNTED TO SEAT IN SAID LATCH SEAT AND BE RETRACTED THEREFROM AND A CYLINDRICAL DIAMETRIC PORTION, AND A CENTRALIZER RING MOUNTED IN SAID DRILL STEM TO ABUT AGAINST SAID CYLINDRICAL DIAMETRIC PORTION FOR CENTERING SAID ASSEMBLY WHEN THE ASSEMBLY IS IN A LATCHED POSITION, SAID APPARATUS BEING FURTHER CHARACTERIZED IN THAT THE DRILL BIT HAS AN INWARDLY EXTENDING ANNULAR FLANGE AND THAT THE CORE BARREL ASSEMBLY HAS A SERRATED INNER END THAT SEATS IN SAID FLANGE. 